AUTOMATIC HEADER HEIGHT CONTROL

摘要

The method for automatically controlling the height of a header (12) used with a farm implement (10) comprises the steps of: sensing the height of the header above ground; selecting a desired height of the header above ground; determining any difference error between the selected height and the sensed height; determining the direction of the difference error, up or down; generating an electrical correction pulse having a duty cycle directly related to the amount of the difference error; supplying the electrical correction pulse to solenoid operated valving means to cause same to supply and/or relieve a pulse of pressurized fluid to a mechanism for raising or lowering the header; and repeating the above steps automatically and continuously to move the header (12) in intermittent pulses toward the selected height, thereby automatically to control the height of the header (12) above ground. The apparatus for carrying out the method comprises: a potentiometer (24) for sensing the height of the header above ground, a potentiometer (44) for selecting a desired height of the header above ground, and a mulifunction electrical circuit (80) coupled to the sensing potentiometer (24) and the selecting potentiometer (44). The circuit (80) is capable of (a) determining the difference error between the selected height and the sensed height, (b) determining the direcion of the difference error, up or down, (c) generating an electrical correction pulse having a duty cycle directly related to the amount of difference error, (d) supplying the electrical correction pulse to the solenoid operated valving mens (108) to cause same to supply and/or relieve a pulse of pressurized fluid to the mechanism for raising or lowering the header (12) and (e) repeatedly determining the difference error and direction of the difference error, and cyclically generating correction pulse and supplying the correction pulses to the solenoid operated valving means (108) to move the header (12) in intermittent pulse toward the selected height, thereby automatically to control the height of the header (12) above ground.